Application of Artificial Neural Network for Analysis of Triangular Plate with Hole Considering Different Geometrical and Loading Parameters

In this study, Artificial Neural Network has been employed for analysis of triangular plate with different geometrical and loading parameters. Plates, having different sizes of concentric holes are analyzed. Finite element analysis for 81 cases is carried out using ANSYS Workbench 15.0 software. Using these data of FEM analysis an Artificial Neural Network has been trained. The successfully trained network is further used for analysis of four new cases which are also validated by using ANSYS Workbench 15.0 software.

Effect of size on biaxial flexural strength for cement-based materials by using a triangular plate method

The effect of size on the biaxial flexural strength(BFS)of Portland cement mortar was investigated by using the recently proposed triangular plate method(TPM).An experimental program was conceived to study the size effect by keeping a constant water-cement ratio of 0.485,cement-sand ratio of 1:2.75,and using unreinforced triangular mortar plates of five different thicknesses and seven different side lengths.The BFS of the produced specimens was tested,and variations of BFS depending on specimen thickness and side length were determined.The results indicated that increases in triangular plate specimen side length and specimen thickness led to a decrease in the BFS of Portland cement mortar.The effect of specimen length increase on BFS was more significant than on the effect of the specimen thickness.The variations in specimens’thickness indicated a deterministic Type I size effect,while the variations in specimens’length showed an energetic-statistical Type I size effect.

TRIANGULAR ELEMENTS FOR REISSNER-MINDLIN PLATE

A general method to construct locking free Reissner-Mindlin plate elements is presented. According to this method the shear strain is replaced by its proper interpolation polynomial, which corresponds to the Kirchoff conditions at the interpolation points as the thickness of plate tends to zero, so the element is locking free. We construct two triangular elements by this method - a 3-node element and a 6-node element. The numerical results are provided.

钢框架-核心筒辐射钢梁的快速安装技术研究

基于工程实际,探讨钢框架-核心筒结构辐射钢梁快速安装施工技术。通过在混凝土核心筒预埋件节点位置预先加设2块三角码板,达到吊装机械能够快速脱钩、撤吊的施工目标,并采用预先加长连接板近埋件端长度的方式,消除混凝土核心筒结构因模板支设、混凝土浇筑变形等施工误差导致的钢梁扩孔、钢梁切割等一系列严重质量问题,显著提高辐射钢梁施工效率,提升核心筒预埋连接节点区施工质量。

基于板-梁理论的双轴对称三角形管翼缘工字形梁组合扭转的理论研究及有限元验证

基于板-梁理论推导双轴对称三角形管翼缘工字形悬臂梁的总应变能方程,得到梁的翘曲刚度和自由扭转刚度,然后通过外力势能和总应变能得到总势能方程。再依据能量变分模型、微分方程模型及边界条件得出悬臂梁端部最大扭转角公式,将求出的最大扭转角与用ANSYS建立的有限元模型计算结果进行对比。结果表明,悬臂梁在端扭矩作用下的扭转角理论值与有限元值较为接近,误差最小的绝对值为2.40%,最大的绝对值为4.44%,可为工程设计提供参考。

高速公路曲线双幅连续钢桁梁桥设计

江苏省常熟市的常福公路分离式立交桥主桥采用(85+125+75.08)m三跨连续下承式钢桁梁,分左右两幅布置,单幅桥采用两片带竖杆的三角桁作为主桁,主桁中心距为22.25 m。主桥平面位于半径为6496 m的圆曲线上,设计考虑制造、安装方便,每片主桁分别在两个中支点及中跨中心处设置3个弯折点,有效减小加宽宽度。单幅桥主桁横断面采用平行四边形布置,内外侧主桁杆件高度与桁高保持一致,主桁中心高差为40.5 cm,横联及桥门架设置横坡。主桥采用顶推施工方法,以减小建设期对航运的影响。桥梁主桁的位置选择与折弯节点板的处理方式,可供类似工程设计参考。

Development of quadrilateral spline thin plate elements using the B-net method

The quadrilateral discrete Kirchhoff thin plate bending element DKQ is based on the isoparametric element Q8, however, the accuracy of the isoparametric quadrilateral elements will drop significantly due to mesh distortions. In a previous work, we constructed an 8-node quadrilateral spline element L8 using the triangular area coordinates and the B- net method, which can be insensitive to mesh distortions and possess the second order completeness in the Cartesian co- ordinates. In this paper, a thin plate spline element is devel- oped based on the spline element L8 and the refined tech- nique. Numerical examples show that the present element indeed possesses higher accuracy than the DKQ element for distorted meshes.

大倾角伪俯斜工作面下端头支护阻力研究

大倾角走向长壁伪俯斜工作面顶板破断具有不同于真倾斜工作面的时序性和分区性,其顶板垮落充填特征极大影响了下端头支护安全性,需要针对下端头进行支护优化。采用数值计算、物理相似模拟实验、理论分析等综合方法,结合多个大倾角伪俯斜工作面实验与现场经验,分析了大倾角伪俯斜工作面顶板垮落充填规律和下端头顶板结构形成特征,建立了下端头三角板力学模型,提出了端头支架支护阻力计算公式。结果表明:大倾角伪俯斜工作面顶板垮落、滑移、充填交错发生,对采空区下部充填具有不均匀性,基本顶破断呈“U-X-O”动态演化过程,工作面下端头形成梯阶弧形三角板结构,弧形三角板传递至端头支架的载荷呈二次函数曲线分布,得到了下端头无充填时端头支架所需工作阻力计算公式。通过枣泉煤矿大倾角综放开采工程应用,确定了端头支架最小工作阻力为8 091.866 kN,选取ZTHJ11400/15.5/25型横式端头支架,保证了端头顶板结构的动态稳定,减少了端头漏冒事故,取得了良好支护效果。

Numerical simulation of heat transfer and flow of cooling air in triangular wavy fin channels

Numerical computation models of air cooling heat transfer and flow behaviors in triangular wavy fin channels(TWFC) were established with structural parameters of fins considered.The air side properties of heat transfer coefficient and pressure drop are displayed with variable structural parameters of fins and inlet velocities of cooling air.Within the range of simulation,TWFC has the best comprehensive performance when inlet velocity vin=4-10 m/s.Compared with those of straight fins,the simulation results reveal that the triangular wavy fin channels are of higher heat transfer performances especially with the fin structural parameters of fin-height Fh=9.0 mm,fin-pitch Fp=2.5-3.0 mm,fin-wavelength λ=14.0-17.5 mm and fin-wave-amplitude A=1.0-1.2 mm.The correlations of both heat transfer factor and friction factor are presented,and the deviations from the experimental measurements are within 20%.

The great triangular seismic region in eastern Asia:Thoughts on its dynamic context

A huge triangle-shaped tectonic region in eastern Asia plays host to numerous major earth- quakes. The three boundaries of this region, which contains plateaus, mountains, and intermountain basins, are roughly the Himalayan arc, the Tianshan-Baikal, and longitude line -105°E. Within this trian- gular region, tectonism is intense and major deformation occurs both between crustal blocks and within most of them. Outside of this region, rigid blocks move as a whole with relatively few major earthquakes and relatively weak Cenozoic deformation. On a large tectonic scale, the presence of this broad region of intraplate deformation results from dynamic interactions between the Indian, Philippine Sea-West Pacific, and Eurasian plates, as well as the influence of deep-level mantle flow. The Indian subcontinent, which continues to move northwards at -40 mm/a since its collision with Eurasia, has plunged beneath Tibet, resulting in various movements and deformations along the Himalayan arc that diffuse over a long distance into the hinterland of Asia. The northward crustal escape of Asia from the Himalayan collisional zone turns eastwards and southeastwards along 95°-100°E longitude and defines the eastern Himalayan syntaxis. At the western Himalayan syntaxis, the Pamirs continue to move into central Asia, leading to crustal deformation and earthquakes that are largely accommodated by old EW or NW trending faults in the bordering areas between China, Mongolia, and Russia, and are restricted by the stable landmass northwest of the Tianshan-Altai-Baikal region. The subduction of the Philippine and Pacific plates under the Eurasian continent has generated a very long and narrow seismic zone along trenches and island arcs in the marginal seas while imposing only slight horizontal compression on the Asian continent that does not impede the eastward motion of eastern Asia. In the third dimension, there may be southeastward deep mantle flow beneath most of Eurasia that reaches the marginal seas and may contribute to extension along the eastern margin of Eurasia.

Double Symplectic Eigenfunction Expansion Method of Free Vibration of Rectangular Thin Plates

The free vibration problem of rectangular thin plates is rewritten as a new upper triangular matrixdifferential system.For the associated operator matrix,we find that the two diagonal block operators are Hamiltonian.Moreover,the existence and completeness of normed symplectic orthogonal eigenfunction systems of these two blockoperators are demonstrated.Based on the completeness,the general solution of the free vibration of rectangular thinplates is given by double symplectic eigenfunction expansion method.

含柔性动平台并联机器人动力学建模方法研究

针对含柔性动平台的空间并联机器人刚柔耦合问题,基于Bézier三角形与绝对节点坐标法提出一种高阶柔性三角形厚板单元模型和连续性约束条件,基于该模型分析动平台变形状态及其对系统动力学特性的影响。利用自然坐标法与绝对节点坐标法建立刚柔耦合系统动力学模型,通过引入板单元第4个面积坐标的二阶梯度来描述厚度方向上的变形并解决泊松闭锁问题,结合广义-α法与牛顿迭代法求解动力学方程,并对系统静力学模型和动力学模型进行仿真分析。结果表明,动平台在运动过程中产生的周期性凹陷变形对机器人空间位姿的影响与机构布局方式、质量分布和负载作用方式完全一致,系统刚性构件与柔性动平台的运动耦合方式符合多体动力学模型的非线性规律;运动轨迹误差低于1.2×10^(-12)mm,动力学方程和约束方程迭代误差均小于设定阈值10^(-6)和10^(-14),求解精度能满足工程应用要求;基于不同参数开展仿真对比分析,验证了所述方法的有效性和通用性。

功能梯度材料三角形截面梁组合扭转理论研究

基于板-梁理论,首先,推导了功能梯度材料(Functionally Gradient Materials,FGM)三角形截面扭转变形的总应变能与总势能;然后,以悬臂梁在端部作用集中扭矩为例,依据能量变分原理,得到能量微分模型;再求解得到三角形截面悬臂梁在端部扭矩作用下最大扭转角的表达式;最后,用有限元软件ANSYS建立了相应的有限元模型进行求解,并将有限元结果与理论结果进行对比。结果表明:悬臂梁在端扭矩作用下的扭转角理论值与有限元值较为接近,误差最小绝对值为2.77%,最大绝对值为4.29%。该结论可为工程设计提供参考。

基于高阶理论的加筋复合材料夹芯结构屈曲有限元模型

加筋复合材料夹芯结构由于面板与夹芯层的力学性能差异较大,层间剪切变形明显,层间剪切应力对结构的屈曲特性影响非常明显.此外筋条与面板之间横向剪切变形也会显著地影响加筋夹芯结构的屈曲特性.因此,需要发展一种能准确计算面板与芯体之间、筋条与板之间横向剪切应力的模型来分析复合材料加筋夹芯结构的屈曲特性.文章推导了正弦型整体-局部高阶剪切变形理论,该理论满足面内位移、横向剪切应力连续条件和自由表面条件,并且未知量个数独立于加筋夹芯板的层数.基于此理论,结合离散的Kirchhoff三角形单元(DKT单元)构造了正弦型整体-局部高阶三角形板单元(SGLT),该单元满足面内位移在厚度方向的锯齿分布和横向剪切应力层间连续性条件,并通过两个数值算例验证了模型的准确性.随后评估了金属面板加筋夹芯板和复合材料面板格栅加筋夹芯板在各种几何、材料参数和边界条件下的屈曲特性.数值分析结果表明,建立的有限元模型能准确地预测加筋复合材料夹芯结构的屈曲行为.并且相较于三维有限元模型,建立的模型具有更高的计算效率.

射流脉冲喷头驱动板结构优化对喷头性能的影响研究

目前缺乏对射流脉冲喷头流道结构的整体优化和基于喷洒特点的驱动结构设计与研究。为解决这一问题,推动该型国产喷头产业化进程与后续系列喷头开发,对射流脉冲喷头进行了整体结构优化设计,并针对影响射流脉冲喷头转动和水量分布较大的驱动板结构进行了首创设计与试验研究,解决了驱动机构复杂,弹簧易腐蚀老化的缺陷。同时驱动板结构是影响射流脉冲喷头水力性能的关键因素之一,而当前缺少基于喷洒特点的驱动结构设计与研究,因此,采用四因素三水平水力性能试验与验证相结合的方法,提出“爪形”驱动板结构。正交试验结果表明:“爪形”驱动板各结构因素对射流脉冲喷头喷灌均匀度影响主次顺序为三角形挡板底宽、驱动板长度、驱动板倾角、驱动板宽度;最优结构为三角形挡板底宽7 mm、驱动板长度18 mm、驱动板倾角14°、驱动板宽度11 mm。

三角形管翼缘工字形梁扭转振动推导及有限元验证

为了使三角形管翼缘工字形截面构件在实际工程中被方便计算和使用,基于“板-梁”理论,对纯弯扭作用下的单轴对称三角形管翼缘工字形钢梁进行扭转振动分析,利用能量变分原理,推导出悬臂钢梁扭转角公式和简支端自由扭转振动下的频率公式。运用ANSYS软件建立有限元模型并提取扭转角以及频率解进行对比和验证。结果表明,扭转角的理论解与有限元解误差在0.62%~4.08%之间,扭转振动结果误差在-4.02%~-1.35%之间,从而初步证明了文中理论的正确性。研究成果可为单轴对称三角形管翼缘工字形梁扭转振动的工程设计提供参考。

三角形板式节点式钢网壳在大型储罐上的应用

随着网壳在大型储罐中的应用越来越广泛,针对传统三角形板式钢网壳基础零件存在失稳,导致钢网壳整体结构稳定性较差问题,展开三角形板式节点式钢网壳在大型储罐上的应用研究。计算网壳顶静力,为节点式钢网壳数值设计与施工提供基础。使用Xsteel模型构建零件参数化模型,预制节点式钢网壳构件。设定三角形板式节点钢网壳安装工序,实现三角形板式节点式钢网壳在大型储罐的设计安装,构建实验环节,实验结果表明:三角形板式节点式钢网壳可有效提升节点稳定性,进一步降低网壳刚度形变量与网壳可承受最大应力,保证拱顶式储罐在运行过程中的安全性。

玻璃企业硅砂侧卸方案优化

在玻璃生产中,硅砂是广泛使用的主要原料。随着硅砂运输工具的升级,硅砂侧卸车在玻璃企业中得到了广泛的应用。根据现有硅砂侧卸方案的运行状况,通过对劳动强度、质量保证和经济性的分析,提出了适合硅砂侧卸料生产企业应用的优化改进方案。

异形板风塔幕墙的安装技术

上港十四区风塔幕墙是以三角形异形板块为主的幕墙系统,附着于主体结构外圈分区悬挂的圆柱面网格钢结构幕墙支撑结构体系上,结构复杂,安装难度大。为实现幕墙系统的顺利安装,结合结构特点,对幕墙构造进行了细部优化和统一,减少了开模量和加工难度,过程中主要采用“垂直提升、环轨就位”的施工工艺,通过针对性设计的双环轨吊装系统、垂直运输索道及相应辅助设备的配合使用,分区实现了幕墙系统的安装,为此类幕墙的施工积累了一定的经验。

组合式水力空化反应器去除难降解污染物的试验研究

难降解废水因污染物浓度高、组分复杂,化学结构稳定,难以降解处理,成为工业废水治理的难题之一.常规处理方法限制因素较多,水力空化处理废水具有设计简单,易于操作,便于企业应用等优点,因而具有广阔的应用前景.试验研究了三角形孔口多孔板与文丘里管组合的水力空化对亲水性与疏水性难降解混合污染物的降解情况.结果表明:多孔板的孔口流速、孔口大小、孔口数量、污染物的初始浓度以及多孔板与文丘里管的先后顺序等对污染物的降解率有重要影响.